1. Technical Field
The present invention relates to an apparatus for injection molding.
2. Description of Related Art
Injection molding has been widely used for manufacturing plastic, vitreous, or metal articles.
Referring to FIG. 6, a typical apparatus for injection molding includes an injection unit 550 and a mold unit 580. The injection unit 550 may include a nozzle 510 and a screw (not shown) movable in the nozzle 510 for bringing materials to the tip of the nozzle 510. The mold unit 580 may include a mold 520, a sprue bushing 530 inserted in the mold 520, and a mounting block 560 for positioning the sprue bushing 530. The sprue bushing 530 is for communicating with the nozzle 510 and transmitting the materials to the mold 520. The sprue bushing 530 has an orifice 535 at an end thereof. The nozzle 510 is dipped into the orifice 535 during injection molding, and is detached away from the orifice 535 when the injection molding process is completed. The sprue bushing 530 and the nozzle 510 each have a spherical end surface for closely contacting with each other. However, in case abrasion of the spherical end surfaces occurs, the spherical end surfaces of the nozzle 510 and the sprue bushing 530 may no longer closely contact with each other, and thus materials 540 may flow out.
In addition, it is difficult to make the spherical end surfaces to be closely matched with each other, referring to FIG. 7, a gap 640 may exist between the spherical end surfaces of a nozzle 610 and a sprue bushing 630, therefore, additional time is required for machining the spherical end surfaces of the nozzle 610 and the sprue bushing 630.
What is needed, therefore, is an apparatus for injection molding, which can overcome the above shortcomings.